System for displaying images and method for fabricating the same

ABSTRACT

Systems for displaying images and fabrication method thereof are provided. A representative system incorporates an electroluminescent device including light emitting units emitting lights with different luminescent intensities along light emitting paths thereof, formed overlying a substrate. And a compensation layer is disposed along the light emitting paths to adjust the different luminescent intensities for outputting substantially uniform light.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a system for displaying images and a method offabricating the same.

2. Description of the Related Art

Currently, display devices, such as liquid crystal devices and ELdevices, are increasingly used as displays of electronic devices, suchas cellular phones and portable computers. An increasing number of thesedisplay devices are full-color displays.

A significant factor in display manufacturing is the performance of thedisplay, or the uniformity of light emitted from the luminescentelement. The luminescent element, however, may not generate equivalentlight. Thus, an electroluminescent device with uniform light performanceand the method for fabricating the same is desirable.

SUMMARY OF THE INVENTION

The invention provides an electroluminescent device capable ofgenerating uniform light performance and a method for fabricating thesame.

Systems for displaying images are provided. An exemplary embodiment ofsuch as system comprises an electroluminescent device. Theelectroluminescent device comprises light emitting units emitting lightswith different luminescent intensities along light emitting pathsthereof, formed overlying a substrate; and a compensation layer disposedalong the light emitting paths to adjust the different luminescentintensities thereof for outputting substantially uniform light.

A method for manufacturing a system for displaying images is provided.The system comprises an electroluminescent device. A substrate isprovided. Light emitting units emitting lights with differentluminescent intensities along light emitting paths thereof are formedoverlying the substrate. A photosensitive layer is disposed along thelight emitting paths. Lights from the light emitting units areirradiated to the photosensitive layer, such that the photosensitivelayer changes to form an irradiated photosensitive layer with differenttransmittances in different regions corresponding to the lights receivedwith different luminescent intensities for outputting substantiallyuniform light.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIGS. 1A to 1B are cross sections illustrating manufacture of anembodiment of an electroluminescent device.

FIG. 2 is a schematic cross-sectional view of an embodiment of a bottomemission type organic electroluminescent display device.

FIGS. 3 and 4 are schematic cross-sectional view of embodiments of a topemission type organic electroluminescent display device.

FIG. 5 is a block diagram of an embodiment of an electroluminescentdevice with pixel cells.

FIG. 6 schematically shows an embodiment of a system for displayingimages.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

Exemplary embodiments of a system for displaying imagines andfabrication methods for the same will now be described. FIG. 1B shows across section view of an embodiment of a system for displaying images,which includes an electroluminescent device 100. FIG. 1A to 1Billustrate a method for manufacturing a system for displaying images.

Referring to FIG. 1A, a substrate 10 is provided. Light emitting unitsEL1˜EL3 emitting lights L1˜L3 with different luminescent intensities aresituated on the substrate 10. In general, the lights L1˜L3 withdifferent luminescent intensities are emitted along light emitting pathsP₁˜P₃. Each light emitting unit EL1˜EL3 can include a light emittinglayer 50 sandwiched between a first electrode layer 40, such as ananode, and a second electrode layer 60, such as a cathode. Optionally, adielectric layer 70 may be formed on the second electrode layer 60.Specifically, the dielectric layer 70 is made of an organic resinmaterial and is formed to cover the edge of the anode 40 for preventingshort circuits between the anode 40 and the subsequently-formed cathode60. The dielectric layer 70 is formed of one selected from the groupconsisting of silicon nitride, silicon oxynitride, and silicon oxide.

Subsequently, a compensation layer is disposed along the light emittingpaths L1˜L3 to adjust the different luminescent intensities thereof foroutputting substantially uniform light L0. In this case, thecompensation layer can be disposed overlying the light emitting unitsEL1˜EL3 or underlying the substrate 10.

As shown in FIG. 1A, for example, a photosensitive layer 30 with anoriginal transmittance is first disposed along the light emitting pathsL1˜L3, such as overlying the light emitting units EL1˜EL3. In FIG. 1B,the photosensitive layer 30 is then irradiated by the lights L1˜L3 fromthe light emitting units EL1˜EL3 to form an irradiated photosensitivelayer 30′ serving as the compensation layer which changes to havedifferent transmittances in different regions 30 a˜30 c corresponding tothe lights received with different luminescent intensities.

In one example, light L1 from the light emitting unit EL1, with higherluminescent intensity, irradiates to the photosensitive layer 30 alongthe path P₁. Light L2 from the light emitting unit EL2, with lowerluminescent intensity, irradiates to the photosensitive layer 30 alongthe path P₂. Thus, the irradiated photosensitive layer 30′ changes orgenerally decreases to have different transmittances in the regions 30 aand 30 b corresponding to the light emitting units EL1 and EL2. In thiscase, the irradiated photosensitive layer in the first region 30 achanges to have a lower transmittance, since it is irradiated with lightL1 of higher luminescent intensity. The irradiated photosensitive layerin the second region 30 b does not change its transmittance or change tohave a higher transmittance than that of the first region, since it isirradiated with light L2 of lower luminescent intensity. Alternatively,the irradiated photosensitive layer in the first region 30 a does notchange its transmittance, and the irradiated photosensitive layer in thesecond region 30 b changes to have a higher transmittance. Thus, lightoutput of the light emitting units EL1 and EL2 can be compensated, sincelight L1 with higher luminescent intensity passes through the region 30a with lower transmittance and light L2 with lower luminescent intensitypasses through the region 30 b with higher transmittance.

Then, the irradiated photosensitive layer 30′ is fixed to have a fixedproperty with different transmittances in different regions. Forexample, the irradiated photosensitive layer 30′ can be performed bydeveloping to fix the transmittance property.

Thus, as described above, by means of the irradiated photosensitivelayer 30′ with different transmittances serving as a compensation layer,non-uniform luminescent intensities of lights L1˜L3 emitted from thelight emitting units EL1˜EL3 are adjusted to produce uniform orsubstantially uniform light output L₀. “Substantially uniform” meansthat the light preferably varies about ±10% in luminescent intensity,more preferably about ±5% in luminescent intensity, and most preferablyabout ±2% in luminescent intensity over the whole panel.

In some embodiments, the photosensitive layer 30 may be any materialthat can change transmittance after irradiation by light, specifically,any material that can change, such as decrease to differenttransmittance after irradiation by light with different luminescentintensities. Representative examples of the photosensitive layer 30include a negative film, a conjugated polymer, and a silver-containingcompound such as a silver halide.

Further, in one example, the light emitting units EL1˜EL3 comprise anorganic electroluminescent element, which includes organic ororganometallic material that produces light. Hereinafter, the termorganic will be taken to include both purely organic and organometallicmaterials. The light emitting layer 50 can be a single pure materialwith a high luminescent efficiency. For example, a well-known materialfor this purpose is tris(8-quinolinolato-N1,08)aluminum (Alq), whichproduces excellent green electroluminescence.

In this case, the substrate 10 provides mechanical support for the lightemitting units EL1˜EL3 and for electrical leads connecting the lightemitting units to a current source. The cathode 60, or both the anode 40and the substrate 10, can be transparent to the electroluminescentlight, allowing that light to be viewed. The term transparent refers tothe ability to transmit no less than 80 percent of theelectroluminescent light. In a variant of this structure, the cathode,rather than the anode, rests upon the substrate. In that variant, eitherthe anode, or both the cathode and the support substrate, aretransparent to the electroluminescent light. When the cathode and anodeare connected to a current source (not shown), recombining in the lightemitting unit to produce electroluminescent light.

Referring to FIG. 1B again, electroluminescent device 100 may be anactive matrix OLED display device (AMOLED) comprising a plurality ofpixels according to an exemplary embodiment of the invention. To achievesubstantially uniform light output, each light emitting unit EL1˜EL3preferably serves as a sub-pixel in a pixel cell.

Moreover, the principles of the invention can be applied to either a topemission type organic electroluminescent display device or a bottomemission type organic electroluminescent display device.

For example, in FIG. 2, a schematic cross-sectional view of an exemplarybottom emission type organic electroluminescent display device 120 isillustrated. Organic light emitting diodes EL1˜EL3 similar to thestructure as shown in FIG. 1B are disposed overlying a transparentsubstrate 12 and a covering layer 80 is formed thereon. In this case, alower electrode serving as an anode 40 is formed of the transparentconductive material, while an upper electrode serving as a cathode 60 isformed of the opaque conductive material. Thus, the lights emitted fromthe organic light emitting diodes EL1˜EL3 are released in a bottomdirection.

An important feature is forming, preferably attaching irradiatedphotosensitive layer 32 with different transmittances in differentregions underlying the substrate 12 to adjust the non-uniformluminescent intensities of lights L1˜L3 emitted from the light emittingunits EL1˜EL3 to produce substantially uniform light output L₀.

FIG. 3 illustrates a schematic cross-sectional view of an exemplary topemission type organic electroluminescent display device 130. Organiclight emitting diodes EL1˜EL3 are disposed overlying a substrate 13. Inthis case, a lower electrode serving as an anode 40 is formed of theopaque conductive material, while an upper electrode serving as acathode 60 is formed of transparent conductive material. Thus, thelights emitted from the organic electroluminescent diodes EL1˜EL3 arereleased in an upward direction.

A feature is forming, preferably depositing irradiated photosensitivelayer 34 with different transmittances on the organic light emittingdiodes EL1˜EL3 to adjust the non-uniform luminescent intensities oflights L1˜L3 emitted from the light emitting units EL1˜EL3 to producesubstantially uniform light output L₀. In this case, covering layer 80is formed to cover the irradiated photosensitive layer 34 and theorganic light emitting diodes EL1˜EL3.

As a modification, in FIG. 4, a schematic cross-sectional view of a topemission type organic electroluminescent display device 140 is shown.Covering layer 80 may be first formed to cover the organic lightemitting diodes EL1˜EL3, and an irradiated photosensitive layer 36 withdifferent transmittances is then formed on the covering layer 80.

Thus, the irradiated photosensitive layer may be disposed in variouslocations. In some embodiments, the irradiated photosensitive layer isdisposed between the light emitting units EL1˜EL3 and the covering layer80. In some embodiments, the irradiated photosensitive layer is disposedunder the substrate or over the covering layer.

As described above, in some embodiments, the transparent conductivematerial may be a conductive and transparent metal oxide. For example,indium tin oxide (ITO) has been widely used as the transparent electrodebecause of its transparency, good conductivity, and high work function.Furthermore, the opaque conductive material may be a metal having a lowwork function, such as aluminum or silver.

Another important feature is described with reference to FIG. 2˜FIG. 4.In these embodiments, the irradiated protective layer 32, 34 and 36 maybe removed from the attached surface and then be putted into a developertank to develop for fixing the transmittance property thereof. Afterthat, the irradiated protective layer 32, 34 and 36 with fixedtransmittance property can be reattached again. Moreover, it is possibleto put the entire organic electroluminescent display device with theirradiated protective layer 32 or 36 directly into the developer tank todevelop, while the irradiated protective layer 32 or 36 is secured tothe outside surface of the covering layer 80 or the substrate 12 asshown in FIG. 2 and FIG. 4.

Thus, the use of the irradiated photosensitive layer with differenttransmittances may permit the light output of an electroluminescentdevice to be substantially uniform.

An alternative embodiment of the invention will be described withreference to FIG. 5, which is a cross section of an embodiment of asystem for displaying images, which includes an electroluminescentdevice 300. According to this embodiment, the irradiated photosensitivelayer 30′ with different transmittances of FIG. 1B is removed. Instead,the differences between the original emitting lights L1˜L3 from lightemitting units EL1˜EL3 and the uniform output light L0 are transformedinto corresponding digital compensation values which can be stored in acompensation unit 370. For example, the differences in light intensitybetween the emitting lights L1˜L3 and the substantially uniform light L0can be calculated and then be transformed into the corresponding digitalcompensation values.

Referring to FIG. 5, the electroluminescent device 300 comprises aplurality of pixel cells 310 arranged in an array. In this case, eachpixel cell 310 comprises sub-pixels EL1˜EL3. However, the pixel orsubpixel is generally used to designate the smallest addressable unit ina display panel. For a monochrome display, there is no distinctionbetween pixel and subpixel. The term “subpixel” is used in multicolordisplay panels and is employed to designate any portion of a pixel,which can be independently addressable to emit a specific color. In afull-color display, a pixel generally comprises three primary-colorsubpixels, namely blue, green, and red.

In one example, the compensation unit 370 comprises a memory 330 storingthe corresponding digital compensation values and a display controller350 coupled to the memory 330. The subpixels EL1˜EL3 are addressed withcolumn drivers 320 and row drivers 340, which are controlled by thedisplay controller 350 of the compensation unit 370. Therefore, thedisplay controller 350 controls the column drivers 320 to adjust theluminescent intensities operative to supply a plurality of signals tothe subpixels EL1˜EL3 to display images, based on the correspondingdigital compensation values from the memory unit 330. The method ofmanufacturing the electroluminescent device 300 of FIG. 5 is similar tothat of manufacturing the electroluminescent device 100 of FIGS. 1A˜1B,except that the irradiated photosensitive layer 30′ is removed andreplaced by the compensation unit 370.

As described above, the compensation unit 370 may control the columndrivers 320 to adjust the luminescent intensities of each subpixel asshown in FIG. 1B, by using the digital compensation values.Specifically, the digital compensation values stored in the memory unit330 is adapted to decrease the light with higher luminescent intensityor increase the light with lower luminescent intensity. Therefore, thelight output L0 of the electroluminescent device 300 can be adjusted tobe uniform or substantially uniform.

FIG. 6 schematically shows another embodiment of a system for displayingimages which, in this case, is implemented as a display panel 400 or anelectronic device 600. The described electroluminescent device 100, 200,and 300 in FIGS. 1B to 5 can be incorporated into a display panel thatcan be an OLED panel. As shown in FIG. 6, the display panel 400comprises an electroluminescent device 300 shown in FIG. 5, such as theactive matrix organic electroluminescent device. The display panel 400can form a portion of a variety of electronic devices (in this case,electronic device 600). Generally, the electronic device 600 cancomprise the display panel 400 and an input unit 500. Further, the inputunit 500 is operatively coupled to the display panel 400 and providesinput signals (e.g., an image signal) to the display panel 400 togenerate images. The electronic device 600 can be a mobile phone,digital camera, PDA (personal digital assistant), notebook computer,desktop computer, television, car display, or portable DVD player, forexample.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1-16. (canceled)
 17. A method for manufacturing a system for displayingimages, wherein the system comprising an electroluminescent device, themethod comprising: providing a substrate; forming light emitting unitsemitting lights with different luminescent intensities along lightemitting paths thereof overlying the substrate; disposing aphotosensitive layer along the light emitting paths; and irradiating thelights from the light emitting units to the photosensitive layer, suchthat the photosensitive layer changes to form an irradiatedphotosensitive layer with different transmittances in different regionscorresponding to the lights received with different luminescentintensities for outputting substantially uniform light.
 18. The methodas claimed in claim 17, wherein the irradiated photosensitive layercomprises a first region and a second region, the method furthercomprising: irradiating light with a higher luminescent intensity to thefirst region to form a lower transmittance; and irradiating light with alower luminescent intensity to the second region to form a highertransmittance than the first region.
 19. The method as claimed in claim17, further comprising fixing the irradiated photosensitive layer tohave a fixed property with different transmittances in differentregions.
 20. The method as claimed in claim 19, wherein the step offixing is performed by developing.
 21. The method as claimed in claim17, further comprising: removing the irradiated photosensitive layer;fixing the irradiated photosensitive layer to have a fixed property withdifferent transmittances in different regions; and reattaching theirradiated photosensitive layer.
 22. The method as claimed in claim 20,further comprising: removing the irradiated photosensitive layer;transforming differences between the emitting lights from light emittingunits and the substantially uniform light into corresponding digitalcompensation values; storing the corresponding digital compensationvalues; and adjusting the luminescent intensities operative to supply aplurality of signals to the light emitting units to display images,based on the corresponding digital compensation values.
 23. The methodas claimed in claim 22, wherein the transforming step comprises:calculating the differences in light intensity between the emittinglights from light emitting units and the substantially uniform light;and transforming the differences in light intensity therebetween intothe corresponding digital compensation values.